Question: during the morning commute to work a person has to...

During the morning commute to work, a person has to cross 20 traffic lights. if the probability that each traffic light is green as the person approaches that traffic light is 0.2, determine the following:

a. the probability of finding exactly 5 traffic lights green during the commute.

b. the probability of finding the number of traffic lights green during the commute lies between 3 and 6.